Electronic pen

ABSTRACT

An electronic pen configured to transmit signals to a sensor of a position detecting device includes a core body; a signal transmitter which transmits a signal for position detection and a signal including information about the electronic pen to the sensor of the position detecting device; and a protector which sets at least a tip of the core body between a protected state and an unprotected state. In response to at least the tip of the core body being in the unprotected state, the signal for position detection and the signal including the information are transmitted from the signal transmitter to the sensor of the position detecting device. In response to at least the tip of the core body being in the protected state, the signal for position detection is transmitted from the signal transmitter and the signal including the information is not transmitted from the signal transmitter.

BACKGROUND Technical Field

The present invention relates to an electronic pen that is a pen-typeposition indicator used with a position detecting device.

Description of the Related Art

The electronic pen is held by a user and is used for position indicationover a sensor of a position detecting device. The indicated positionover the sensor by the electronic pen is detected by the positiondetecting device through transfer of a signal for position detectionbetween the electronic pen and the sensor based on various couplingsystems, such as the electromagnetic induction coupling system and thecapacitive coupling system.

In recent years, between the electronic pen and the position detectingdevice, additional information, such as writing pressure data andidentification information of the electronic pen, has come to betransferred besides the signal for position detection. For example, seePatent Document 1 (Japanese Patent Laid-Open No. 2014-67265).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: Japanese Patent Laid-Open No. 2014-67265

BRIEF SUMMARY Technical Problems

Identification information and so forth as additional information of anelectronic pen is information that should be kept secret, if possible,and is information for which security management is desired, ifpossible. Furthermore, the additional information is information thatshould be sent out to a position detecting device when a user iscarrying out position indication operation over a sensor by theelectronic pen, and should not be unnecessarily transmitted, ifpossible. However, in the past, the additional information, in general,is simultaneously sent out with a signal for position detection.Accordingly, there has been a problem that no consideration is madeabout ensuring security of the additional information and transmissiononly at a time of need.

Furthermore, the recent electronic pens have been decreasing inthickness in consideration of being mounted on small-size portableequipment, such as a mobile phone terminal, in which a positiondetecting device is incorporated. Along with this thickness reduction ofthe electronic pen, thickness reduction is being promoted also in thecore body that is incorporated in the electronic pen and forms the pentip.

Normally, the core body is attached such that its tip protrudes from oneopening of a tubular chassis of the electronic pen. As a result, thecore body becomes vulnerable to a shock due to its thickness reduction,and there is a possibility that the core body gets broken or distortedwhen the electronic pen is dropped. Moreover, recently there are casesin which the material of the core body is made of felt. However, thisfelt is obtained by bundling and bonding fibers and, therefore, thestrength is slightly low. Thus, the bundle of fibers often breaks upwhen an excessive force, such as a shock due to a drop, is applied tothe core body. In particular, the core body made of felt is vulnerableto a large force in a direction perpendicular to the core axis.Therefore, it is important to protect the core body when the electronicpen is not being used.

In view of the above-described problems, the present invention, in oneor more embodiments, intends to provide an electronic pen configured tobe capable of simultaneously solving problems of ensuring of security ofadditional information and avoidance of unnecessary transmission andprotection of a core body.

Technical Solution

In order to solve the above-described problems, an embodiment of theinvention provides an electronic pen that transmits a signal to a sensorof a position detecting device, and is characterized by including a corebody, a signal transmitter or transmitting unit that transmits a signalto the sensor, a protector or a protection mechanism that sets at leasta tip of the core body to a state of not being exposed to an externalenvironment to protect at least the tip of the core body, and a detectoror detecting means that detects whether or not at least the tip of thecore body is in a state of being protected by the protection mechanism.Based on a detection result of the detecting means, a signal forposition detection and a signal including additional information that isto be transmitted to the position detecting device when positionindication operation is carried out over the sensor are allowed to betransmitted from the signal transmitting unit when at least the tip ofthe core body is not protected by the protection mechanism and isexposed to the external. Further, the signal including the additionalinformation is precluded from being transmitted when at least the tip ofthe core body is protected by the protection mechanism.

According to the electronic pen in accordance with an embodiment of theinvention with the above-described configuration, the core body can beprotected by the protection mechanism as the core body does not protrudeto the external when this electronic pen is not used. Thus, the corebody can be protected from shock of a drop or the like.

Furthermore, when it is detected by the detecting means that the tip ofthe core body is protected by the protection mechanism, the additionalinformation is precluded from being sent out based on the detectionresult. Moreover, when it is detected by the detecting means that theprotection of the tip of the core body by the protection mechanism isreleased, the additional information is allowed to be transmitted.

Advantageous Effect

According to the electronic pen in accordance with one or moreembodiments of the present invention, the transmission of the additionalinformation is precluded when the tip of the core body is protected bythe protection mechanism, and the transmission of the additionalinformation is allowed when the protection of the tip of the core bodyby the protection mechanism is released. This can provide an electronicpen configured to be capable of simultaneously solving problems ofensuring of security of the additional information, avoidance ofunnecessary transmission of the additional information, and protectionof the core body.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A and 1B depict diagrams showing a configuration example of afirst embodiment of an electronic pen according to one aspect of thepresent invention.

FIGS. 2A, 2B, and 2C depict diagrams for explaining a configurationexample of an electronic pen cartridge used in the first embodiment ofthe electronic pen according to one aspect of the present invention.

FIG. 3 is a diagram showing a configuration example of an electroniccircuit of the first embodiment of the electronic pen according to oneaspect of the present invention with a circuit configuration example ofa position detecting device.

FIG. 4 is a diagram showing a flowchart for explaining operation of themajor part of the first embodiment of the electronic pen according toone aspect of the present invention.

FIGS. 5A, 5B, and 5C depict diagrams showing a configuration example ofa second embodiment of the electronic pen according to one aspect of thepresent invention.

FIG. 6 is a diagram showing a configuration example of an electroniccircuit of the second embodiment of the electronic pen according to oneaspect of the present invention with the circuit configuration exampleof the position detecting device.

FIG. 7 is a diagram showing a flowchart for explaining operation of themajor part of the second embodiment of the electronic pen according toone aspect of the present invention.

FIG. 8 is a diagram showing a configuration example of a thirdembodiment of the electronic pen according to one aspect of the presentinvention.

FIG. 9 is a diagram showing part of the configuration example of thethird embodiment of the electronic pen according to one aspect of thepresent invention.

FIG. 10 is a diagram showing a configuration example of an electroniccircuit of the third embodiment of the electronic pen according to oneaspect of the present invention.

FIG. 11 is a diagram showing a configuration example of a positiondetecting device used with the third embodiment of the electronic penaccording to one aspect of the present invention.

FIG. 12 depicts diagrams for explaining a signal sent out from the thirdembodiment of the electronic pen according to one aspect of the presentinvention.

FIGS. 13A and 13B depict diagrams for explaining a configuration exampleof a fourth embodiment of the electronic pen according to one aspect ofthe present invention.

FIGS. 14A and 14B depict diagrams for explaining a configuration exampleof a fifth embodiment of the electronic pen according to one aspect ofthe present invention.

DETAILED DESCRIPTION

Several embodiments of an electronic pen according to several aspects ofthe present invention will be described below with reference to thedrawings.

First Embodiment

FIGS. 1A and 1B depict diagrams showing a configuration example of afirst embodiment of the electronic pen according to an aspect of thepresent invention. An electronic pen 1 of the first embodiment has aknock-type configuration in which an electronic pen cartridge 3 thatforms an electronic pen main body unit is housed in a hollow part 2 a ofa tubular chassis 2 and a pen tip of the electronic pen cartridge 3 isprotruded and retracted from the side of an opening 2 b at one end ofthe chassis 2 in the longitudinal direction by a knock cam mechanismunit 4. The knock cam mechanism unit 4 forms a protection mechanism inthis example.

FIG. 1A shows the state in which the entire electronic pen cartridge 3,including the pen tip side (tip of a pen tip part 313 of a core bodyunit 31 to be described later) of the electronic pen cartridge 3, ishoused in the hollow part 2 a of the chassis 2, and the pen tip isprotected by the protection mechanism. FIG. 1B shows the state in whichat least the tip of the pen tip of the electronic pen cartridge 3protrudes from the opening 2 b of the chassis 2 by the knock cammechanism unit 4, and the protection by the protection mechanism isreleased. The examples of FIGS. 1A and 1B are shown as the state inwhich the chassis 2 of the electronic pen 1 is composed of a transparentsynthetic resin and the inside thereof is see-through.

The electronic pen 1 of the present embodiment is configured to ensurecompatibility with a commercially-available knock-type ballpoint pen.Specifically, the chassis 2 and the knock cam mechanism unit 4 providedin this chassis 2 have the same configuration as a well-knowncommercially-available knock-type ballpoint pen, and the dimensionalrelationship is also configured identically. In other words, it is alsopossible to use the chassis and the knock cam mechanism unit of thecommercially-available knock-type ballpoint pen as they are as thechassis 2 and the knock cam mechanism unit 4. Furthermore, for theelectronic pen cartridge 3, compatibility with a refill 6 of a ballpointpen is ensured as will be described later. The electronic pen cartridge3 has a configuration in which the electronic pen cartridge 3 is housedin the chassis 2 instead of the refill 6 (see FIG. 2A) of a ballpointpen and the pen tip can protrude and retract based on a knock system bythe knock cam mechanism unit 4.

As shown in FIGS. 1A and 1B, the knock cam mechanism unit 4 has awell-known configuration in which a cam main body 41, a knock bar 42,and a rotary element 43 are combined. The cam main body 41 is formed onthe inner wall surface of the tubular chassis 2. An end part 42 a of theknock bar 42 is made to protrude from an opening 2 c on the oppositeside to the pen tip side of the chassis 2 so that a knock operation by auser can be accepted. The rotary element 43 has a fitting part 43 a towhich an end part of the electronic pen cartridge 3 on the opposite sideto the pen tip side is fitted.

When the end part 42 a of the knock bar 42 is pressed down in the stateof FIG. 1A, the electronic pen cartridge 3 is locked into the state ofFIG. 1B in the chassis 2 by the knock cam mechanism unit 4, whichprovides the state in which the pen tip side of the electronic pencartridge 3 protrudes from the opening 2 b of the chassis 2. Then, whenthe end part 42 a of the knock bar 42 is pressed down again from thisstate of FIG. 1B, the locked state is released by the knock cammechanism unit 4 and the position of the electronic pen cartridge 3 inthe chassis 2 returns to the state of FIG. 1A by a return spring 5. Thedetailed configuration of the knock cam mechanism unit 4 and theoperation thereof are well known and therefore description thereof isomitted here.

[Embodiment of Electronic Pen Cartridge]

FIGS. 2A, 2B, and 2C depict diagrams showing a configuration example ofthe electronic pen cartridge 3 with comparison with a refill of acommercially-available knock-type ballpoint pen. Specifically, FIG. 2Ashows the refill 6 of the commercially-available knock-type ballpointpen, and FIG. 2B shows a configuration example of the electronic pencartridge 3 of the present embodiment. Furthermore, FIG. 2C is a diagramfor explaining the configuration of the major parts of the electronicpen cartridge 3 of the present embodiment shown in FIG. 2B.

As shown in FIG. 2A, the refill 6 of the commercially-availableknock-type ballpoint pen has a well-known configuration in which a pentip part 61 in which a ball is disposed at the tip and an ink storage 62are joined at a joint part 63 and are integrated. The joint part 63 hasthe same diameter as the ink storage 62.

On the other hand, the electronic pen cartridge 3 of the presentembodiment has a configuration in which the core body unit 31 and atubular body unit 32 are joined to be integrated as shown in FIG. 2B. Asshown in FIG. 2C, the core body unit 31 has a configuration in which acoil 311 is wound partly around a magnetic core, specifically a ferritecore 310 in this example, and the part thereof around which the coil 311is not wound is covered by a protective material 312 to form the pen tippart 313.

In this example, in the core body unit 31, the coil 311 is wound arounda part with approximately half length of the total length of the ferritecore 310 from the vicinity of one end part of the ferrite core 310.Furthermore, in this example, the remaining part with approximately halflength in the ferrite core 310, around which the coil 311 is not wound,is covered by the protective material 312 that is composed of, forexample, a resin and is used as the pen tip part 313. In one embodiment,a resin material that is comparatively hard and has elasticity, such aspolyoxymethylene (POM), is used for the protective material 312 of thepen tip part 313.

In this case, as shown in FIG. 2A and FIG. 2B, the configuration is somade such that the diameter and length of the pen tip part 313 of thecore body unit 31 of the electronic pen cartridge 3 are substantiallyequal to diameter R1 and length L1 of the pen tip part 61 of the refill6 of the ballpoint pen. Furthermore, the configuration is so made suchthat the diameter of the part around which the coil 311 is wound in thecore body unit 31 of the electronic pen cartridge 3 is substantiallyequal to diameter R2 (R2>R1) of the ink storage 62 of the refill 6 ofthe ballpoint pen.

Furthermore, the tubular body unit 32 is composed of a first tubularbody unit 321 in which electronic circuit components are disposed, and asecond tubular body unit 322 in which components for writing pressuredetection are disposed. Moreover, as shown in FIGS. 2A and 2B, thelength (total length) in the state in which the core body unit 31 andthe tubular body unit 32 are joined is selected to be equal to totallength L2 of the refill 6 of the ballpoint pen.

A printed board 33 is disposed in the first tubular body unit 321 of thetubular body unit 32 as shown in FIG. 2C. In addition, an electroniccircuit 34 including a capacitor that forms a resonant circuit with thecoil 311, a memory that stores identification information(identification (ID)) forming part of additional information that shouldbe sent out to a position detecting device when a user is carrying outposition indication operation over the sensor by the electronic pen, anintegrated circuit (IC), and so forth are provided on the printed board33.

Furthermore, the core body unit 31 and the first tubular body unit 321of the tubular body unit 32 are joined to be integrally configured inthe state in which part of the ferrite core 310 of the core body unit 31is inserted in the first tubular body unit 321, for example. In thiscase, in the joining between the core body unit 31 and the first tubularbody unit 321 of the tubular body unit 32, a winding start end 311 a anda winding finish end 311 b of the coil 311 are electrically connected toone end and the other end of the capacitor provided in the electroniccircuit 34 in the first tubular body unit 321.

In this example, the second tubular body unit 322 is formed of a tubularbody with the diameter substantially equal to the diameter R2 of the inkstorage 62 of the refill 6 of the commercially-available ballpoint pen.In the example of FIG. 2B, the second tubular body unit 322 is dividedinto two parts of a longer part 322 a and a shorter part 322 b, and awriting pressure detecting member 36 is provided near a joint part 35 ofthem.

Specifically, as shown in FIG. 2C, the longer part 322 a and the shorterpart 322 b are joined at the joint part 35 with the intermediary of alinking bar member 351 and a coil spring 352 in this example. In thiscase, the longer part 322 a and the shorter part 322 b are alwayselastically displaced to be separated from each other in the axialcenter direction by the coil spring 352. However, the longer part 322 aand the shorter part 322 b are configured to be locked at predeterminedpositions by the linking bar member 351 so as not to be displaced in theaxial center direction beyond the positions. Furthermore, theconfiguration is made such that the total length of the electronic pencartridge 3 in the locked state is substantially equal to the totallength L2 of the refill 6 of the above-described ballpoint pen.

Moreover, as shown in FIG. 2C, the writing pressure detecting member 36is provided in the longer part 322 a in the present embodiment.Furthermore, the configuration is so made such that the side of one end351 a of the linking bar member 351 works as a pressing part of thewriting pressure detecting member 36.

The writing pressure detecting member 36 of this example can employ aconfiguration of a variable-capacitance capacitor that uses writingpressure detecting means with a well-known configuration described in aPatent Document: Japanese Patent Laid-Open No. 2011-186803, for example,and whose capacitance changes according to the writing pressure. It isalso possible to employ a configuration using a semiconductor elementthat allows the capacitance to vary according to the writing pressurelike one disclosed in Japanese Patent Laid-Open No. 2013-161307, forexample.

When pressure is applied to the core body unit 31 in the state in whichthe electronic pen cartridge 3 is housed in the chassis 2, a force fromthe pressure causes the longer part 322 a of the electronic pencartridge 3 to move to the side of the shorter part 322 b against theelastic force of the coil spring 352, and the capacitance of the writingpressure detecting member 36 changes according to the writing pressure.

The electronic pen cartridge 3 with the above configuration is housed inthe chassis 2 by fitting the shorter part 322 b of the tubular body unit32 of the electronic pen cartridge 3 to the fitting part 43 a of therotary element 43 of the knock cam mechanism unit 4. In this state, thewhole of the electronic pen cartridge 3, including the core body unit 31thereof, is housed in the chassis 2, and the core body unit 31 of theelectronic pen cartridge 3 is protected.

Furthermore, in the electronic pen 1 of the present embodiment, whenusing the electronic pen 1 with a position detecting device, the userpresses down the end part 42 a of the knock bar 42 to protrude the tipof the pen tip part 313 of the core body unit 31 from the opening 2 b ofthe chassis 2 as shown in FIG. 1B. As a result, the protection of thecore body unit 31 of the electronic pen cartridge 3 is released. Then,when the use of the electronic pen 1 ends, the user presses down the endpart 42 a of the knock bar 42 again to house the whole of the electronicpen cartridge 3 in the hollow part 2 a of the chassis 2 as shown in FIG.1A and protect the core body unit 31.

[Circuit Configuration of Electronic Pen 1 and Circuit Configuration ofPosition Detecting Device Used with Electronic Pen 1]

FIG. 3 shows a circuit configuration example of the electronic circuit34 of the electronic pen 1, and a circuit configuration example of aposition detecting device 200 that carries signal transfer based onelectromagnetic induction coupling with the electronic pen 1.

In the present embodiment, the electronic pen 1 is configured to makeelectromagnetic induction coupling with conductors of a sensor of theposition detecting device 200 to thereby transfer a signal for positiondetection and transmit, to the position detecting device 200, writingpressure information detected through the writing pressure detectingmember 36, and identification information (ID) of the electronic pen 1itself or identification information (ID) of the electronic pencartridge 3.

Specifically, in the electronic circuit 34 of the electronic pencartridge 3, a capacitor 401 is connected in parallel to the coil 311and a parallel resonant circuit 40R is formed.

Furthermore, the electronic circuit 34 includes a control circuit 400that controls transmission of additional information as shown in FIG. 3.In this example, the control circuit 400 is formed as an IC. The IC thatforms the control circuit 400 is configured to operate by a supplyvoltage Vcc obtained by rectifying an alternate current (AC) signalreceived in the parallel resonant circuit 40R from the positiondetecting device 200 by electromagnetic coupling in a rectifying circuit(power supply circuit) 404 composed of a diode 402 and a capacitor 403.

Furthermore, in this example, a switch circuit 405 set to the open statenormally (normal open) is provided between the parallel resonant circuit40R and the power supply circuit 404. The switch circuit 405 is formedof a semiconductor switch circuit, for example, and is in thehigh-impedance state in the open state.

The switch circuit 405 is controlled to be turned on by a switch controlsignal from a switch control circuit 406. The switch control circuit 406generates the switch control signal from the AC signal received in theparallel resonant circuit 40R from the position detecting device 200 byelectromagnetic coupling.

Furthermore, in the electronic circuit 34, a switch circuit 407 isconnected in parallel to the parallel resonant circuit 40R composed ofthe coil 311 and the capacitor 401. The switch circuit 407 is configuredto be on/off-controlled by the control circuit 400. An electromagneticinduction signal transmitted from the position detecting device 200 tothe control circuit 400 is supplied through a capacitor 408 as asynchronization signal for transfer of the electromagnetic inductionsignal between the electronic pen 1 and the position detecting device200.

In the present embodiment, as shown in FIG. 3, a variable-capacitancecapacitor 36C of the writing pressure detecting member 36 is connectedto the control circuit 400. A resistor R is connected in parallel to thevariable-capacitance capacitor 36C. In this example, the control circuit400 discharges the variable-capacitance capacitor 36C through theresistor R after charging the variable-capacitance capacitor 36C, andmeasures the time that elapses for the voltage of the terminal in whichthe variable-capacitance capacitor 36C is connected (equivalent to thevoltage across the variable-capacitance capacitor 36C) to become apredetermined threshold. Thereby, the control circuit 400 measures thecapacitance of the variable-capacitance capacitor 36C.

Then, the control circuit 400 detects change in the writing pressurefrom change in the measured capacitance of the variable-capacitancecapacitor 36C and detects whether a writing pressure is applied to theelectronic pen cartridge 3. In addition, when detecting that a writingpressure is applied, the control circuit 400 calculates the writingpressure value from the value of the capacitance of thevariable-capacitance capacitor 36C.

Furthermore, in the present embodiment, the control circuit 400transmits information on the calculated writing pressure value (writingpressure data) to the position detecting device 200 as a digital signalof plural bits by on/off-controlling the switch circuit 407. In thepresent embodiment, the writing pressure data forms part of additionalinformation.

Moreover, in this example, an ID memory 409 that stores identificationinformation (ID) including the manufacturer number and product number ofthe electronic pen 1 or the electronic pen cartridge 3 is connected tothe control circuit 400. Furthermore, the control circuit 400 reads outthe identification information stored in the ID memory 409 andon/off-controls the switch circuit 407 to transmit the identificationinformation to the position detecting device 200 as a digital signal ofplural bits. In the present embodiment, this identification informationalso forms part of additional information.

In the present embodiment, the control circuit 400 detects whether ornot the tip of the pen tip part 313 of the core body unit 31 of theelectronic pen cartridge 3 is protected, and carries out control to sendout additional information only in the state in which the tip is notprotected. In the present embodiment, the control circuit 400 detectswhether or not the tip of the pen tip part 313 of the core body unit 31of the electronic pen cartridge 3 is protected based on whether or notit is detected, by the writing pressure detecting member 36, that awriting pressure is applied.

Specifically, in the protected state in which the entire electronic pencartridge 3 is housed in the chassis 2, the tip of the pen tip part 313of the core body unit 31 of the electronic pen cartridge 3 does notprotrude to the external, and, thus, a writing pressure is not appliedto the core body unit 31. On the other hand, in the state in which theknock bar of the knock cam mechanism unit 4 has been operated and theprotected state has been released, in which the tip of the pen tip part313 of the core body unit 31 of the electronic pen cartridge 3 protrudesto the external from the opening 2 b of the chassis 2, it is possiblethat a writing pressure is applied to the core body unit 31, and thestate in which a writing pressure is actually applied is the state inwhich the electronic pen 1 is used by a user. Furthermore, in thisexample, when the writing pressure value increases by a predeterminedthreshold or larger from the state in which a writing pressure is notapplied, the control circuit 400 detects it and determines thatapplication of a writing pressure has been started.

As described above, in the control circuit 400, it can be detectedwhether or not the tip of the pen tip part 313 of the core body unit 31of the electronic pen cartridge 3 is protected by detecting whether ornot application of a writing pressure has been started. Specifically, inthe present embodiment, the writing pressure detecting means also has afunction as detecting means for detecting whether or not the tip of thepen tip part 313 of the core body unit 31 of the electronic pencartridge 3 is protected.

In the present embodiment, when detecting that application of a writingpressure has not been started, the control circuit 400 always keeps theswitch circuit 407 is in the off-state to provide the state in which theparallel resonant circuit 40R always works. Furthermore, when detectingthat application of a writing pressure has been started, the controlcircuit 400 transmits writing pressure data and identificationinformation to the position detecting device 200 as an amplitude shiftkeying (ASK)-modulated signal, as described will be later, byon/off-controlling the switch circuit 407 at timings based on thesynchronization signal from the position detecting device receivedthrough the capacitor 408. The data and information may be modulated toan on off keying (OOK) signal instead of the ASK modulation.

In the position detecting device 200, as shown in FIG. 3, an X-axisdirection loop coil group 211X and a Y-axis direction loop coil group212Y are stacked and a position detecting coil is formed. For example,the respective loop coil groups 211X and 212Y are composed of n and m,respectively, rectangular loop coils. The respective loop coilsconfiguring the respective loop coil groups 211X and 212Y are disposedto be lined up at equal intervals and sequentially overlap with eachother.

Furthermore, in the position detecting device 200, a selection circuit213 to which the X-axis direction loop coil group 211X and the Y-axisdirection loop coil group 212Y are connected is provided. The selectioncircuit 213 sequentially selects one loop coil in the two loop coilgroups 211X and 212Y.

Moreover, the position detecting device 200 includes an oscillator 221,a current driver 222, a switching connecting circuit 223, a receivingamplifier 224, a detection circuit 225, a low-pass filter 226, asample/hold circuit 227, an analog to digital (A/D) conversion circuit228, and a processing control unit 229. In one embodiment, theprocessing control unit 229 is a microcomputer.

The oscillator 221 generates an AC signal with a frequency f0.Furthermore, the AC signal generated in the oscillator 221 is suppliedto the current driver 222. The current driver 222 converts the AC signalsupplied from the oscillator 221 to a current and sends out the currentto the switching connecting circuit 223. Based on control from theprocessing control unit 229, the switching connecting circuit 223switches the connection target (transmitting-side terminal T,receiving-side terminal R) to which the loop coil selected by theselection circuit 213 is connected. In these connection targets, thetransmitting-side terminal T and the receiving-side terminal R areconnected to the current driver 222 and the receiving amplifier 224,respectively.

An induced voltage generated in the loop coil selected by the selectioncircuit 213 is sent to the receiving amplifier 224 via the selectioncircuit 213 and the switching connecting circuit 223. The receivingamplifier 224 amplifies the induced voltage supplied from the loop coiland sends out the amplified voltage to the detection circuit 225.

The detection circuit 225 detects the induced voltage generated in theloop coil, i.e., the received signal, and sends out the received signalto the low-pass filter 226. The low-pass filter 226 has a cutofffrequency sufficiently lower than the above-described frequency f0 andconverts the output signal of the detection circuit 225 to a directcurrent (DC) signal to send out the DC signal to the sample/hold circuit227. The sample/hold circuit 227 holds a voltage value at predeterminedtiming of the output signal of the low-pass filter 226, specifically atpredetermined timing in the reception period, and sends out the voltagevalue to the A/D conversion circuit 228. The A/D conversion circuit 228converts the analog output of the sample/hold circuit 227 to a digitalsignal and outputs the digital signal to the processing control unit229.

The processing control unit 229 controls selection of the loop coil inthe selection circuit 213, switching by the switching connecting circuit223, and the timing of the sample/hold circuit 227. The processingcontrol unit 229 causes an electromagnetic induction signal to betransmitted from the X-axis direction loop coil group 211X and theY-axis direction loop coil group 212Y with a certain transmissioncontinuation time based on an input signal from the A/D conversioncircuit 228.

In each loop coil of the X-axis direction loop coil group 211X and theY-axis direction loop coil group 212Y, an induced voltage is generatedby an electromagnetic induction signal transmitted from the electronicpen 1. The processing control unit 229 calculates the coordinate valueof the position indicated by the electronic pen 1 in the X-axisdirection and the Y-axis direction based on the level of the voltagevalue of this induced voltage generated in each loop coil.

Furthermore, the processing control unit 229 supplies a signal forintermittence control of a transmission signal and a signal for controlof the level of the transmission signal to the current driver 222, andexecutes reception processing of additional information, such as writingpressure data and identification information from the electronic pen 1.As described later, the processing control unit 229 detects anintermittent signal formed of an ASK signal from the electronic pen 1 asa digital signal of plural bits and detects additional information, suchas writing pressure data and identification information.

[Operation of Electronic Pen 1 and Operation of Position DetectingDevice 200]

Position detection operation and transmission and reception ofadditional information between the electronic pen 1 and the positiondetecting device 200 will be described below.

The position detecting device 200 sends out an AC signal of atransmission signal based on processing control of the processingcontrol unit 229. In the electronic pen 1, when the electronic pen 1 isnot in the state in which the AC signal from the position detectingdevice 200 is received by the parallel resonant circuit 40R, the switchcircuit 405 is in the off-state and the supply voltage Vcc is notsupplied from the power supply circuit 404. In this state, the controlcircuit 400 stops operation and the switch circuit 407 is set to theoff-state.

Therefore, the electronic pen 1 is in the state in which the AC signalfrom the position detecting device 200 can be received in the parallelresonant circuit 40R. Furthermore, when the electronic pen 1 is broughtabove the sensor of the position detecting device 200 by a user, theelectronic pen 1 becomes the state in which the parallel resonantcircuit 40R of the electronic pen 1 can receive the AC signal from theposition detecting device 200 by electromagnetic induction couplingirrespective of whether or not the electronic pen cartridge 3 is in theprotected state.

Along with this, the switch control circuit 406 of the electroniccircuit 34 of the electronic pen 1 generates the switch control signalthat turns on the switch circuit 405 from the AC signal received by theparallel resonant circuit 40R from the sensor of the position detectingdevice 200. When the switch circuit 405 is turned on due to this, thesupply voltage Vcc generated by rectifying the AC signal received by theparallel resonant circuit 40R is supplied from the power supply circuit404 to the control circuit 400.

When the supply voltage Vcc is supplied, the control circuit 400 startsoperation. FIG. 4 is a flowchart for explaining processing operation ofthe control circuit 400 of the electronic circuit 34 of the electronicpen 1.

First, the control circuit 400 monitors change in the capacitance of thevariable-capacitance capacitor 36C of the writing pressure detectingmember 36 and determines whether or not a writing pressure is appliedthrough the pen tip part 313 of the core body unit 31 of the electronicpen cartridge 3 (step S101). When it is determined in the step S101 thata writing pressure is not applied, the control circuit 400 makes thestate in which transmission of additional information is stopped andkeeps the switch circuit 407 at the off-state constantly (step S102).After the step S102, the control circuit 400 returns the processing tothe step S101 and repeats the processing of the step S101 and thesubsequent steps.

In addition, as described above, the state in which a writing pressureis applied is not obtained when the electronic pen cartridge 3 is allhoused in the chassis 2 and is in the protected state. Thus, the stateof the step S102 includes a time when the electronic pen cartridge 3 isin this protected state.

Application of a writing pressure becomes possible when the end part 42a of the knock bar 42 of the knock cam mechanism unit 4 is pressed downby the user and the tip of the pen tip part 313 of the core body unit 31of the electronic pen cartridge 3 becomes the state in which theprotected state is released and the tip protrudes from the opening 2 bof the chassis 2.

When it is determined that a writing pressure is applied in the stepS101, the control circuit 400 starts transmission of additionalinformation (step S103). Specifically, the control circuit 400calculates a writing pressure value from the measurement result of thecapacitance of the variable-capacitance capacitor 36C formed of thewriting pressure detecting member 36 and generates writing pressuredata. Then, the control circuit 400 on/off-controls the switch circuit407 according to the generated writing pressure data to thereby transmitthe writing pressure data as part of the additional information from theelectronic pen 1 to the position detecting device 200.

Furthermore, in the step S103, the control circuit 400 reads outidentification information of the electronic pen 1 or the electronic pencartridge 3 from the ID memory 409 and on/off-controls the switchcircuit 407 according to the read-out identification information tothereby transmit the identification information as part of theadditional information from the electronic pen 1 to the positiondetecting device 200.

Specifically, when the switch circuit 407 is in the off-state, theparallel resonant circuit 40R can carry out a resonance operation inresponse to an AC signal transmitted from the position detecting device200 and return an electromagnetic induction signal to the positiondetecting device 200. The loop coil of the position detecting device 200receives the electromagnetic induction signal from the resonant circuit40R of the electronic pen 1. In contrast thereto, when the switchcircuit 407 is in the on-state, the parallel resonant circuit 40Rbecomes the state in which the resonance operation in response to the ACsignal from the position detecting device 200 is prohibited. For thisreason, an electromagnetic induction signal is not returned from theparallel resonant circuit 40R to the position detecting device 200, andthe loop coil of the position detecting device 200 does not receive thesignal from the electronic pen 1.

In this example, the processing control unit 229 of the positiondetecting device 200 carries out detection of whether or not a receivedsignal from the electronic pen 1 is present the same number of times asthe number of bits of additional information, and thereby receives theadditional information of a digital signal of these plural bits.

Meanwhile, the control circuit 400 of the electronic pen 1 generates adigital signal of plural bits corresponding to additional information tobe transmitted, and on/off-controls the switch circuit 407 insynchronization with transmission and reception of an electromagneticinduction signal between the electronic pen 1 and the position detectingdevice 200 based on the digital signal of the plural bits. For example,the switch circuit 407 is turned on when the bit of the additionalinformation is “1.” In this case, an electromagnetic induction signal isnot returned from the electronic pen 1 to the position detecting device200 as described above. On the other hand, when the bit of theadditional information is “0,” the switch circuit 407 is turned off. Inthis case, an electromagnetic induction signal is returned from theelectronic pen 1 to the position detecting device 200 as describedabove.

As a result, the processing control unit 229 of the position detectingdevice 200 can receive the additional information that is a digitalsignal by carrying out detection of whether or not a received signalfrom the electronic pen 1 is present the same number of times as thenumber of bits of the additional information.

Next, the control circuit 400 monitors change in the writing pressurebased on the capacitance of the variable-capacitance capacitor 36C ofthe writing pressure detecting member 36, and determines whether or notthe writing pressure has come not to be applied and disappeared (stepS104). When it is determined in the step S104 that the writing pressureis applied and has not disappeared, the control circuit 400 returns theprocessing to the step S103 and repeats the processing of the step S103and the subsequent steps.

Furthermore, when it is determined in the step S104 that the writingpressure has come not to be applied and disappeared, the control circuit400 determines whether or not the disappearance state of the writingpressure has continued for a predetermined time or longer (e.g., 10seconds or longer) (step S105). When it is determined that thepredetermined time or longer has not elapsed, the control circuit 400returns the processing to the step S103 and repeats the processing ofthe step S103 and the subsequent steps. When it is determined in thestep S105 that the disappearance state of the writing pressure hascontinued for the predetermined time or longer, the control circuit 400stops the transmission of the additional information (step S106) andintends protection of security of the additional information.Subsequently in step S106, the control circuit 400 returns theprocessing to the step S101 and repeats the processing of the step S101and the subsequent steps.

That the transmission of the additional information is not immediatelystopped when it is determined that the writing pressure has come not tobe applied and disappeared in the step S104 is based on consideration ofthe case in which the user temporarily separates the electronic pen 1from the sensor surface of the position detecting device 200 althoughcontinuing input with the sensor surface by the electronic pen 1.

When, in the electronic pen 1, the end part 42 a of the knock bar 42 ofthe knock cam mechanism unit 4 is pressed again and the electronic pencartridge 3 is housed in the chassis 2 to be set to the protected state,the disappearance state of the writing pressure continues for thepredetermined time or longer. Therefore, in the protected state of theelectronic pen cartridge 3, the transmission of the additionalinformation from the electronic pen 1 is surely stopped.

Effects of First Embodiment

As described above, in the electronic pen 1 of the above-described firstembodiment, the electronic pen cartridge 3 can be housed in the chassis2 by the knock cam mechanism unit, and the tip of the pen tip part 313of the core body unit 31 of the electronic pen cartridge 3 can beprotruded from the opening of the chassis 2 by operating the knock baraccording to need.

Therefore, in the state in which the electronic pen cartridge 3 ishoused in the chassis 2, the tip of the pen tip part 313 of the corebody unit 31 of the electronic pen cartridge 3 is housed in the chassis2 and thereby can be set to the protected state. Specifically, in thisprotected state, the tip of the pen tip part 313 of the core body unit31 does not protrude to an external environment. Thus, even when theelectronic pen 1 is accidentally dropped, the core body unit 31 of theelectronic pen cartridge 3 does not directly receive the shock of thedrop and is protected.

Furthermore, in this protected state, the additional information such asthe identification information of the electronic pen 1 or the electronicpen cartridge 3 is not transmitted to the position detecting device 200and security of the additional information can be ensured. The state inwhich the electronic pen cartridge 3 is protected is not the state inwhich the electronic pen 1 is used by the user. Thus, this state inwhich transmission of the additional information is stopped alsoprovides an effect that useless signal transmitting can be avoided andthe additional information can be transmitted to the position detectingdevice only when desired.

Furthermore, in the state in which the electronic pen 1 is used in whichthe knock bar has been pressed by the user and the tip of the pen tippart 313 of the core body unit 31 of the electronic pen cartridge 3 isprotruded from the opening of the chassis 2 and a writing pressure isapplied to the pen tip part 313, control is carried out to cause theadditional information to be sent out to the position detecting device200. Therefore, according to the electronic pen 1 of the presentembodiment, the additional information is sent out to the positiondetecting device 200 only in the practical used state by the user. Thus,there is an effect that the transmission of the additional information,which ensuring of security is desired, can be kept to a minimum.

As described above, according to the electronic pen of the firstembodiment, the problem of ensuring of security of the additionalinformation and avoidance of unnecessary transmission and the problem ofprotection of the core body can be simultaneously solved.

Furthermore, in the electronic pen of the above-described firstembodiment, by making the tubular body unit 32 have a thin shape inaddition to the core body unit 31, thickness reduction of the whole ofthe electronic pen cartridge 3 is enabled. This can realize thicknessreduction of the electronic pen 1. In addition, it becomes possible toenable the electronic pen cartridge 3 to have a configuration thatallows ensuring of compatibility with a refill of acommercially-available ballpoint pen as in the above-describedembodiment.

If the electronic pen cartridge 3 has the configuration that allowsensuring of compatibility with a refill of a commercially-availableballpoint pen, there is a merit that the chassis of thecommercially-available ballpoint pen can be diverted as the chassis 2 ofthe electronic pen 1. That is, the electronic pen 1 can be configured byhousing the electronic pen cartridge 3 of the present embodiment insteadof a refill of the ballpoint pen in the chassis of the ballpoint pen.

Modification Example of First Embodiment

The method for the switch control circuit 406 of the electronic circuit34 of the electronic pen 1 to turn on the switch circuit 405 to providethe supply voltage Vcc to the control circuit 400 is not limited to theabove-described method.

For example, it is also possible to have a configuration to send apredetermined digital signal from the position detecting device 200 tothe electronic pen 1 and cause the switch control circuit 406 that hasreceived this digital signal to generate a switch control signal thatturns on the switch circuit 405.

Moreover, in the above-described embodiment, the electronic pencartridge is provided with the writing pressure detecting member and athreshold is set regarding the pressure detected by the writing pressuredetecting member. Furthermore, it is detected that the tip of the pentip part 313 is protected when the pressure detected by the writingpressure detecting member surpasses the threshold. However, a switchthat is turned on according to the pressure applied to the electronicpen cartridge may be provided instead of the writing pressure detectingmember, and it may be detected that at least the tip of the pen tip part313 of the core body unit 31 is protected when this switch is turned on.

Second Embodiment

An electronic pen of the second embodiment is a modification example ofthe first embodiment. In the above-described first embodiment, only oneelectronic pen cartridge is housed in the chassis. In the secondembodiment, plural electronic pen cartridges are housed in the chassis.Furthermore, one of the plural electronic pen cartridges is selected bya knock mechanism, and the tip of the pen tip part of the selectedelectronic pen cartridge is protruded from an opening of the chassis onthe pen tip side and is used.

As described above, the electronic pen cartridge 3 of the electronic pen1 of the first embodiment has a configuration that ensures compatibilitywith the refill 6 of a ballpoint pen. As a commercially-availableballpoint pen, a multicolor ballpoint pen in which refills withdifferent ink colors are mounted exists. The second embodiment providesan electronic pen configured by housing the electronic pen cartridges 3in a chassis with a configuration similar to that of the chassis of thismulticolor ballpoint pen.

FIG. 5A is a configuration diagram showing the appearance of anelectronic pen 1M of the second embodiment. This example of FIG. 5A isalso shown as the state in which a chassis 2M of the electronic pen 1Mis composed of a transparent synthetic resin and the inside thereof issee-through.

The chassis 2M of the electronic pen 1M has the same configuration asthe chassis and knock mechanism of a commercially-available knock-typemulticolor ballpoint pen. The chassis and knock mechanism of acommercially-available knock-type multicolor ballpoint pen may be usedas they are. In this example, three electronic pen cartridges 3B, 3R,and 3E are housed in the chassis 2M.

An opening 2Ma is formed on one end side of the chassis 2M in the axialcenter direction. When any of the electronic pen cartridges 3B, 3R, and3E is slide-moved in the axial center direction by the knock mechanism,the tip of the pen tip part 313 of the core body unit 31 thereof iscaused to protrude to the external through the opening 2Ma.

In the state in which the electronic pen cartridges 3B, 3R, and 3E arenot slide-moved in the axial center direction by the knock mechanism,the whole of the electronic pen cartridges 3B, 3R, and 3E, including thetips of the pen tip parts 313 of the respective core body units 31, ishoused in the hollow part of the chassis 2M and is in the protectedstate as shown in FIG. 5A. Furthermore, as described above, the tip ofthe pen tip part 313 of the core body unit 31 of the electronic pencartridge slide-moved in the axial center direction by the knockmechanism in the electronic pen cartridges 3B, 3R, and 3E is caused toprotrude to the external through the opening 2Ma. Therefore, theabove-described protection is released in the electronic pen cartridgewhose tip of the pen tip part 313 of the core body unit 31 is caused toprotrude to the external through the opening 2Ma by the knock mechanism.

These electronic pen cartridges 3B, 3R, and 3E are configured similarlyto the electronic pen cartridge 3 of the first embodiment in terms ofthe outer shape except for that the electronic pen cartridges 3B, 3R,and 3E are formed with the same dimensions as refills of the multicolorballpoint pen. However, in the electronic pen cartridges 3B, 3R, and 3Eof the case of the second embodiment, the second tubular body unit 322is provided with a switch member that is turned on and off according tomovement in the axial center direction by the knock mechanism as will bedescribed later.

In the electronic pen 1M of the second embodiment, as will be describedlater, based on the state of the switches provided in these electronicpen cartridges 3B, 3R, and 3E, it is detected whether the respectiveelectronic pen cartridges 3B, 3R, and 3E are set to the protected stateby the knock mechanism in the electronic pen 1M. The otherconfigurations of the electronic pen cartridges 3B, 3R, and 3E are setsimilarly to the electronic pen cartridge 3 of the first embodiment.

The knock mechanism of the electronic pen 1M is composed of knock bars42B, 42R, and 42E having fitting parts 42Ba, 42Ra, and 42Ea to which arespective one of the electronic pen cartridges 3B, 3R, and 3E isfitted, a spring receiving member 7, and coil springs 8B, 8R, and 8Edisposed between the fitting parts 42Ba, 42Ra, and 42Ea of a respectiveone of the electronic pen cartridges 3B, 3R, and 3E and the springreceiving member 7.

The spring receiving member 7 is attached to be fixed at a predeterminedposition in the axial center direction in the hollow part of the chassis2M. In the spring receiving member 7, through-holes 7B, 7R, and 7E inwhich second tubular body units 322B, 322R, and 322E of the electronicpen cartridges 3B, 3R, and 3E are inserted are formed. Each of theelectronic pen cartridges 3B, 3R, and 3E is attached to the electronicpen 1M by being inserted in a respective one of the through-holes 7B,7R, and 7E of the spring receiving member 7 and a respective one of thecoil springs 8B, 8R, and 8E and being fitted to the fitting parts 42Ba,42Ra, and 42Ea of the knock bars 42B, 42R, and 42E.

At the part where the knock bars 42B, 42R, and 42E are housed in thechassis 2M, through-hole slits (diagrammatic representation is omittedin FIG. 5A) in which part of the knock bars 42B, 42R, and 42E is exposedto the outside and in which each of the knock bars 42B, 42R, and 42E isenabled to move in the axial center direction are made.

In the electronic pen 1M, as with a well-known multicolor ballpoint pen,when any of the knock bars 42B, 42R, and 42E is slid to the side of theopening 2Ma and the electronic pen 1M becomes the state in which the tipof the pen tip part 313 of the core body unit 31 of any of theelectronic pen cartridges 3B, 3R, and 3E fitted to the knock barprotrudes from the opening 2Ma to the external, a locking part(diagrammatic representation is omitted) of the knock bar 42B, 42R, or42E engages with an engagement part formed in the hollow part of thechassis 2M and the knock bar becomes the locked state in which thelocking part is locked in the state.

Then, when another knock bar is slide-moved to the side of the opening2Ma in the locked state, the lock of the knock bar in the locked stateis released and the knock bar returns to the original state shown inFIG. 5A due to any of the coil springs 8B, 8R, and 8E. Then, the knockbar slide-moved later can become the locked state in which the tip ofthe pen tip part 313 of the core body unit 31 of any of the electronicpen cartridges 3B, 3R, and 3E fitted to the knock bar protrudes from theopening 2Ma to the external.

Subsequently, the electronic pen cartridge whose tip is protruded fromthe opening 2Ma can be changed by slide-moving the knock bar similarly.When slide movement of any of the knock bars 42B, 42R, and 42E isstopped in the middle of becoming the locked state, lock release ofanother knock bar that is currently locked is carried out and the knockbar returns to the protected state of FIG. 5A due to any of the coilsprings 8B, 8R, and 8E.

FIGS. 5B and 5C are diagrams for explaining the switches provided in theelectronic pen cartridges 3B, 3R, and 3E. FIGS. 5B and 5C show theswitch provided in the electronic pen cartridge 3B. The switch issimilarly configured for the other electronic pen cartridges 3R and 3E.

Specifically, when the electronic pen cartridge 3B is fitted to thefitting part 42Ba of the knock bar 42B in the non-locked state, athrough-hole 322Ba is set just in the circumferential surface of thepart of the second tubular body unit 322B housed in the through-hole 7Bof the spring receiving member 7. In addition, in the second tubularbody unit 322B, a switch member 9B is provided in such a manner thatpart thereof is exposed from the through-hole 322Ba.

In one embodiment, the switch member 9B is composed of a material havingelasticity and having electrical conductivity, specifically anelectrically-conductive metal having elasticity. As shown in FIGS. 5Band 5C, the switch member 9B includes a fixed terminal piece 91 fixed tothe inner wall surface near the through-hole 322Ba of the second tubularbody unit 322B, and a movable terminal piece 92 that can be elasticallyin contact with the fixed terminal piece 91. The movable terminal piece92 includes a bent part 92 a configured to be capable of assuming thestate of being elastically in contact with the fixed terminal piece 91and the non-contact state, and is attached to the inside of the secondtubular body unit 322B in such a manner that part of the bent part 92 acan protrude from the through-hole 322Ba.

When the electronic pen cartridge 3B is fitted to the fitting part 42Baof the knock bar 42B in the non-locked state and is in the protectedstate in which the whole of the electronic pen cartridge 3B exists inthe hollow part of the chassis 2M, the switch member 9B is located justin the through-hole 7B of the spring receiving member 7 as shown in FIG.5B. Thus, the bent part 92 a of the movable terminal piece 92 iselastically displaced to the inside of the second tubular body unit 322Bdue to the inner wall of the through-hole 7B, which provides the statein which the fixed terminal piece 91 and the movable terminal piece 92are not in contact with but separated from each other. That is, theswitch member 9B is in the off-state.

When the knock bar 42B is slide-moved to the locked state and the tip ofthe pen tip part 313 of the core body unit 31 of the electronic pencartridge 3B becomes the unprotected state in which the tip protrudesfrom the opening 2Ma of the chassis 2M, the switch member 9B becomes thestate of being out of the through-hole 7B of the spring receiving member7 as shown in FIG. 5C. Along with this, part of the bent part 92 a ofthe movable terminal piece 92 is elastically displaced to protrude fromthe through-hole 322Ba, which provides the state in which the movableterminal piece 92 and the fixed terminal piece 91 are in contact witheach other. That is, the switch member 9B becomes the on-state.

As shown in FIG. 6, the fixed terminal piece 91 and the movable terminalpiece 92 of the switch member 9B are electrically connected to a controlcircuit 400B of an electronic circuit 34B housed in a first tubular bodyunit 321B. The control circuit 400B monitors the on/off-state of theswitch member 9B to thereby detect whether the electronic pen cartridge3B is in the protected state in which the whole of the electronic pencartridge 3B exists in the hollow part of the chassis 2M or in theunprotected state in which the tip of the pen tip part 313 of the corebody unit 31 of the electronic pen cartridge 3B protrudes from theopening 2Ma of the chassis 2M by the knock bar 42B.

Similarly, also in the electronic pen cartridge 3R and the electronicpen cartridge 3E, switch members 9R and 9E (diagrammatic representationis omitted) are provided in the second tubular body unit 322R and 322Eare connected to control circuits 400R and 400E (diagrammaticrepresentation is omitted) of electronic circuits 34R and 34E(diagrammatic representation is omitted) housed in first tubular bodyunits 321R and 321E.

Although FIG. 6 shows the relationship between the electronic pencartridge 3B in the electronic pen 1M and the position detecting device200, it goes without saying that the relationship between the electronicpen cartridges 3R and 3E of the electronic pen 1M and the positiondetecting device 200 is also similar.

Furthermore, in the case of the present embodiment, the positiondetecting device used with the electronic pen cartridges 3B, 3R, and 3Ehas a function of receiving and discriminating identificationinformation transmitted from each of the electronic pen cartridges 3B,3R, and 3E. That is, the position detecting device of the case of thepresent embodiment discriminates the difference among the electronic pencartridges 3B, 3R, and 3E and implements the functions assigned to arespective one of the electronic pen cartridges 3B, 3R, and 3E.

For example, a function of representing a locus (character or graphic)displayed according to the indicated position thereof by black isassigned to the electronic pen cartridge 3B; a function of representinga locus displayed according to the indicated position thereof by red isassigned to the electronic pen cartridge 3R; and a function of erasing alocus indicated and input previously according to the indicated positionthereof is assigned to the electronic pen cartridge 3E. In the presentembodiment, information to notify these character colors and informationto notify the erasure function are stored in the ID memory 409 inaddition to the identification information of the electronic pen 1M andthe electronic pen cartridges 3B, 3R, and 3E.

The information to notify these character colors and information tonotify the erasure function are included, in addition to theidentification information of the electronic pen 1M and the electronicpen cartridges 3B, 3R, and 3E, in additional information sent out fromthe electronic pen cartridges 3B, 3R, and 3E.

The function assigned to the electronic pen cartridge may not only bethe display color of the locus according to the indicated position as inthis example, but may also be the thickness of the locus, the type ofline displayed, such as a solid line, a dotted line, or a one-dot chainline, and so forth.

[Operation of Electronic Pen Cartridges 3B, 3R, and 3E]

Transmission operation of additional information in the electronic pencartridges 3B, 3R, and 3E of the electronic pen 1M will be describedbelow. However, because the electronic pen cartridges 3B, 3R, and 3Ecarry out similar operations, description will be made by taking thecase of the electronic pen cartridge 3B as an example here. Exchangebetween each of the electronic pen cartridges 3B, 3R, and 3E and theposition detecting device 200 is similar to the case of the firstembodiment and therefore description thereof is omitted here.

FIG. 7 is a flowchart for explaining processing operation oftransmission control of additional information in the control circuit400B of the electronic circuit 34B of the electronic pen cartridge 3B.

The control circuit 400B determines whether or not the switch member 9Bhas been turned on by knock operation (slide movement operation) of theknock bar 42B by a user (step S201). When it is determined that theswitch member 9B is not in the on-state but in the off-state in the stepS201, the control circuit 400B deems that the electronic pen cartridge3B is all housed in the chassis 2M and is in the protected state, andmakes the state in which transmission of additional information isstopped and keeps the switch circuit 407 at the off-state constantly(step S202). After the step S202, the control circuit 400B returns theprocessing to the step S201 and repeats the processing of the step S201and the subsequent steps.

When it is determined that the switch member 9B is in the on-state inthe step S201, the control circuit 400B determines that knock operation(slide movement operation) of the knock bar 42B has been carried out bythe user and the tip of the pen tip part 313 of the core body unit 31 ofthe electronic pen cartridge 3B is in the unprotected state in which thetip protrudes from the opening 2 b of the chassis 2, and startstransmission of additional information (step S203).

Specifically, the control circuit 400B transmits writing pressure datato the position detecting device 200 as the additional information.Furthermore, the control circuit 400B reads out the identificationinformation of the electronic pen 1M or the electronic pen cartridge 3Band information to notify the character color from the ID memory 409,and transmits the read-out identification information and information tonotify the character color to the position detecting device 200 as theadditional information. In the case of the electronic pen cartridge 3E,the erasure function is notified instead of the notification of thecharacter color.

Next, the control circuit 400B determines whether or not the switchmember 9B has been turned off (step S204). When it is determined thatthe switch member 9B has not been turned off, the control circuit 400Breturns the processing to the step S203 and repeats the processing ofthe step S203 and the subsequent steps.

Furthermore, when it is determined that the switch member 9B has beenturned off in the step S204, the control circuit 400B determines thatthe electronic pen cartridge 3B has returned to the protected state inwhich the whole of the electronic pen cartridge 3B is housed in thehollow part of the chassis 2M by knock operation of the knock bar 42R or42E of another electronic pen cartridge 3R or 3E, and stops thetransmission of the additional information (step S205) to intendprotection of security of the additional information. Subsequent to thestep S205, the control circuit 400B returns the processing to the stepS201 and repeats the processing of the step S201 and the subsequentsteps.

As described above, according to the electronic pen 1M of the secondembodiment, the problem of ensuring of security of the additionalinformation and the problem of protection of the core body can besimultaneously solved also in the state in which plural electronic pencartridges are housed in one chassis 2M.

In the above-described second embodiment, the switch members 9B, 9R, and9E are used as detecting means that detects the protected state and theunprotected state according to slide movement of the electronic pencartridges 3B, 3R, and 3E in the axial center direction by the knockmechanism. However, the detecting means is not limited thereto.

For example, instead of the switch members, optical sensors may beprovided at corresponding positions on the second tubular body unit. Inthis case, when the electronic pen cartridges 3B, 3R, and 3E are in theprotected state, the optical sensors are located in the through-holes7B, 7R, and 7E of the spring receiving member 7 and are in such a stateas not to receive light. On the other hand, when the electronic pencartridges 3B, 3R, and 3E become the unprotected state, the opticalsensors are located outside the through-holes 7B, 7R, and 7E of thespring receiving member 7 and become the state of being capable ofreceiving light through the transparent chassis 2M. Therefore, each ofthe control circuit 400B, 400R, and 400E can detect whether theelectronic pen cartridge 3B, 3R, or 3E is in the protected state or inthe unprotected state by monitoring the level of the light receptionoutput of the optical sensor.

Third Embodiment

The electronic pens 1 and 1M of the above-described first embodiment andsecond embodiment are the case of the electromagnetic induction couplingsystem in which transfer of a signal for position detection andadditional information is carried out with the position detecting device200 by electromagnetic induction coupling. However, the electronic penof the present invention is not limited to the electronic pen of theelectromagnetic induction coupling system and may be an electronic penof the capacitive coupling system that carries out transfer of signalswith a position detecting device by capacitive coupling. A thirdembodiment is an example of an electronic pen of this capacitivecoupling system and is an example of a transmission-type electronic pen.

FIG. 8 shows the outline of the mechanical configuration of anelectronic pen 1C of the third embodiment. The electronic pen 1C of thisexample is composed of an electronic pen main body 1Ca and a cap 1Cbthat engages with this electronic pen main body in such a manner as tocover the side of a core body 506 serving as the pen tip of theelectronic pen main body 1Ca. In FIG. 8, a diagram is made by breakingpart of the electronic pen main body 1Ca and the cap 1Cb and showing theinside thereof. Furthermore, an enlarged sectional view for explainingthe internal configuration of the part on the pen tip side of theelectronic pen main body 1Ca, which is not broken in FIG. 8, is shown inFIG. 9. Moreover, FIG. 10 is a diagram showing an internal circuitconfiguration example of the electronic pen 1C.

The electronic pen main body 1Ca includes a case 501 that forms achassis formed into a circular tubular shape elongated in the axialcenter direction. The case 501 is composed of a case main body 502composed of an electrically-conductive material, a pen tip sleeve 503that is joined to the case main body 502 and is composed of anelectrically-conductive material, and a lid portion 504 composed of anon-electrically-conductive material.

A pen tip guard member 505 composed of an insulating material is fittedand provided at the end part of the pen tip sleeve 503 on the pen tipside. The core body 506 is composed of an electrically-conductivematerial, such as a resin into which metal powders are mixed in. Asshown in FIG. 9, the core body 506 is inserted into a through-hole 505 aof the pen tip guard member 505 from an opening 501 a in the state ofbeing freely movable in the axial center direction.

In the hollow part of the case main body 502, a board holder 507, abattery 508, and a core body holder 509 are housed as shown in FIGS. 8and 9.

The board holder 507 is composed of an insulating resin, such as aliquid crystal polymer, and includes a holding part (hereinafter,referred to as holding part for components for pressure sensing) 507 afor a writing pressure detecting module 70 as an example of pressuredetecting means and a printed board placement base 507 b. The positionof the board holder 507 is restricted so that the board holder 507 maybe prevented from moving to the side of the core body 506 in the axialcenter direction in the case main body 502.

A terminal conductor 510 that electrically abuts against a positiveterminal 508 a of the battery 508 is provided at the end part of theprinted board placement base 507 b on the side of the lid portion 504.The terminal conductor 510 is electrically connected to a copper foilpattern of a power supply line of a printed board 511. Furthermore, asshown in FIG. 8, a coil spring terminal 512 composed of anelectrically-conductive metal that is electrically connected to anegative terminal 508 b of the battery 508 and is connected to an earthconductor of the printed board 511 is provided at the press-fitting partof the lid portion 504 into the case main body 502. The earth conductorof the printed board 511 is not connected to the case main body 502 andthe pen tip sleeve 503.

In the present embodiment, as shown in FIG. 10, a transmission circuit102 that generates a signal to be sent out from the core body 506 of theelectronic pen 1C, a control circuit 101 that controls activation andthe transmission operation state of this transmission circuit 102, apower supply circuit 103, and so forth, and peripheral circuitcomponents thereof are provided on the printed board 511.

The core body holder 509 is composed of an electrically-conductivematerial and has a shape in which a housing fitting part 509 a in whichan electrically-conductive elastic member 513 composed ofelectrically-conductive rubber, for example, is fitted and housed, and abar-shaped part 509 b fitted to the writing pressure detecting module 70are monolithically formed. The core body 506 is fitted to and held bythe core body holder 509 with the intermediary of theelectrically-conductive elastic member 513 but is configured to becapable of being withdrawn from the core body holder 509 through pullingby a predetermined force. The bar-shaped part 509 b of the core bodyholder 509 is fitted to a holding member 73, as will be described later,in the writing pressure detecting module 70 in the holding part 507 afor components for pressure sensing in the board holder 507.

A coil spring 515 composed of an electrically-conductive material, suchas an electrically-conductive metal, is mounted on the bar-shaped part509 b of the core body holder 509. The core body holder 509 isconfigured to be always biased to the side of the core body 506 relativeto the board holder 507 by the coil spring 515.

Furthermore, in the present embodiment, for the board holder 507, amember for an electrical connection is formed by a conductor terminalmember 516 provided to straddle the holding part 507 a for componentsfor pressure sensing and the coil spring 515 composed of anelectrically-conductive material. By this member, for an electricalconnection, an electrical connection for signal supply from thetransmission circuit 102 of the printed board 511 is realized (see FIG.9). As shown in FIG. 9, the conductor terminal member 516 is composed ofan abutting plate part 516 a against which one end of the coil spring515 abuts and an extending part 516 b for connecting the abutting platepart 516 a and a copper foil part connected to a signal supply terminalof the transmission circuit 102 of the printed board placement base 507b across the part of the holding part 507 a for components for pressuresensing in the board holder 507. A signal from the transmission circuit102 is supplied to the core body 506 inserted and fitted into theelectrically-conductive elastic member 513 via the conductor terminalmember 516, the coil spring 515, the core body holder 509, and theelectrically-conductive elastic member 513.

The writing pressure detecting module 70 of this example is providedwith a configuration of a variable-capacitance capacitor whosecapacitance changes according to the writing pressure applied to thecore body 506. The writing pressure detecting module 70 in the presentembodiment is formed by using, for example, a well-knownvariable-capacitance capacitor described in Japanese Patent Laid-OpenNo. 2011-186803.

Components for pressure sensing that form the writing pressure detectingmodule 70 of this example includes plural components, a dielectric 71, aterminal member 72, the holding member 73, an electrically-conductivemember 74, and an elastic member 75, as shown in FIG. 9. Thesecomponents for pressure sensing that form the writing pressure detectingmodule 70 are lined up in the axial center direction and are housed inthe hollow part of a tubular body 517 of the holding part 507 a forcomponents for pressure sensing in the board holder 507.

The variable-capacitance capacitor formed as the writing pressuredetecting module 70 of this example is formed through sandwiching of thedielectric 71 between the terminal member 72 that forms one electrode ofthe variable-capacitance capacitor and the electrically-conductivemember 74 that forms the other electrode. The terminal member 72 and theelectrically-conductive member 74 are connected to the copper foilpattern of the printed board 511 across a wall part.

Furthermore, the holding member 73 that holds theelectrically-conductive member 74 is configured to be movable in theaxial center direction in the tubular body 517. Moreover, the holdingmember 73 is always biased to the core body side by the elastic member75 formed of a coil spring composed of an electrically-conductivematerial. The electrically-conductive member 74 is electricallyconnected to the elastic member 75, and one end 75 a of the coil springthat forms the elastic member 75 is connected to the copper foil patternof the printed board 511 as the other electrode of thevariable-capacitance capacitor.

In the holding member 73, a recess 73 a is made on the side as the sideof the core body 506 in the axial center direction thereof as shown inFIG. 9. The bar-shaped part 509 b of the core body holder 509 ispress-fitted into the recess 73 a of the member 73 and is engaged so asnot to fall off to the side of the core body 506.

When a pressure is applied to the tip part of the core body 506, thecore body 506 and the core body holder 509 are displaced to the side ofthe lid portion 504 in the axial center direction according to thepressure. Due to this displacement, the holding member 73 in the holdingpart 507 a for components for pressure sensing is displaced to the sideof the dielectric 71 against the elastic biasing force of the elasticmember 75. As a result, the electrically-conductive member 74 fitted tothe holding member 73 is displaced to the side of the dielectric 71, sothat the distance between the electrically-conductive member 74 and thedielectric 71 and the contact area between the electrically-conductivemember 74 and the dielectric 71 change according to the pressure appliedto the core body 506. Due to this, the capacitance of thevariable-capacitance capacitor that forms the writing pressure detectingmodule 70 changes according to the pressure applied to the core body506, so that the change in the capacitance is detected by the controlcircuit 101 and the writing pressure is detected.

Furthermore, in the electronic pen 1C of the third embodiment, the cap1Cb is put on the side of the core body 506 of the electronic pen mainbody 1Ca and thereby the tip of the core body 506 protruding from theopening 501 a of the case 501 of the electronic pen main body 1Ca isprotected. That is, in the third embodiment, the cap 1Cb works as aprotection mechanism for the core body 506 protruding from the opening501 a of the electronic pen main body 1Ca.

Moreover, in the third embodiment, the cap 1Cb becomes the state ofbeing locked to the case 501 by screwing to the case 501 of theelectronic pen main body 1Ca. For this purpose, as shown in FIG. 8, ascrew part 521 is made on the inner wall surface of a hollow part 520 ofthe cap 1Cb. Meanwhile, a screw part 518 that screws to the screw part521 of the cap 1Cb is formed in the case main body 502 of the electronicpen main body 1Ca.

Furthermore, the cap 1Cb and the case main body 502 are provided with apermanent magnet 522 and a magnetic sensor 519, respectively, atpositions that become the state of being opposed to each other when thecap 1Cb screws to the case main body 502. The magnetic sensor 519 thatdetects magnetic flux from the permanent magnet 522 forms detectingmeans about whether or not the tip of the core body of the electronicpen 1C is protected.

Therefore, in the state in which the cap 1Cb is screwed and joined tothe case main body 502, the magnetic flux from the permanent magnet 522provided in the cap 1Cb is detected by the magnetic sensor provided inthe case main body 502 and it is detected that the core body 506 is inthe protected state. Furthermore, in the state in which the cap 1Cb isreleased from the joining to the case main body 502 and the core body506 is exposed to the external, the magnetic flux from the permanentmagnet 522 of the cap 1Cb cannot be detected in the magnetic sensor 519and, thus, it can be detected that the core body 506 is in theunprotected state based on the output of the magnetic sensor 519 at thetime.

As shown in FIG. 8, the magnetic sensor 519 is electrically connected toan electrically-conductive pattern of the printed board 511.Specifically, as shown in FIG. 10, the magnetic sensor 519 is connectedto the control circuit 101 provided on the printed board 511.

[Operation Control of Electronic Pen 1C of Third Embodiment]

FIG. 10 is a block diagram showing the configuration of an electroniccircuit of the major part of the electronic pen 1C of the thirdembodiment, centered around the above-described control circuit 101 andtransmission circuit 102. As shown in the FIG. 10, the battery 508 isconnected to the power supply circuit 103. In the power supply circuit103, the supply voltage of the transmission-type electronic pen 1C ofthe present embodiment is generated and is supplied to the controlcircuit 101 and the transmission circuit 102. In this example, thecontrol circuit 101 is formed as an IC.

The transmission circuit 102 internally includes an oscillator(diagrammatic representation is omitted) in this example and generatesand outputs a transmission signal based on an oscillation signal fromthis oscillator. In this example, the transmission signal from thetransmission circuit 102 is supplied to the core body 506, which is anelectrical conductor, and this transmission signal is transmitted to theposition detecting device 200C through the core body 506.

The control circuit 101 is a microcomputer in this example and controlsactivation of the transmission operation of the transmission circuit 102and controls the transmission operation state thereof. In this controlof the transmission operation state, amplitude control of theoscillation signal from the oscillator included in the transmissioncircuit 102, control of the intermittence of the oscillation signal, andso forth are included.

Furthermore, the control circuit 101 monitors capacitance Cv of avariable-capacitance capacitor 70C formed of the writing pressuredetecting module 70, and detects the value of the writing pressureapplied to the core body 506 from the capacitance Cv of thevariable-capacitance capacitor 70C similar to the above-describedembodiments.

Moreover, an ID memory 104 that stores identification information (ID)of the electronic pen 1C is connected and the magnetic sensor 519 isconnected to the control circuit 101 as described above. The controlcircuit 101 monitors the sensor output of the magnetic sensor 519 anddetermines whether or not the core body 506 is in the state of beingprotected by the cap 1Cb.

In the present embodiment, when it is determined that the core body 506is in the state of being protected by the cap 1Cb from the sensor outputof the magnetic sensor 519, the control circuit 101 carries out controlto keep additional information composed of writing pressure data and theidentification information in the ID memory 104 from being sent out tothe position detecting device 200C.

Furthermore, when it is determined that the present state is the statein which the core body 506 is not protected by the cap 1Cb and isexposed, i.e., the state in which the electronic pen 1C is used, fromthe sensor output of the magnetic sensor 519, the control circuit 101calculates writing pressure data and reads out the identificationinformation from the ID memory 104 and carries out control to send outadditional information composed of them to the position detecting device200C.

The flow of the above-described transmission control of additionalinformation by the control circuit 101 is similar to the transmissioncontrol of additional information by the control circuits 400B, 400R,and 400E of the electronic pen of the second embodiment shown in FIG. 7.However, in the steps corresponding to the step S201 and the step S204,the control circuit 101 determines whether or not the core body 506 isin the state of being protected by the cap 1Cb from the sensor output ofthe magnetic sensor 519 instead of detecting the on-state or off-stateof the switch members 9B, 9R, and 9E.

In the case of the electronic pen 1C of the third embodiment, in stepscorresponding to the step S202 and the step S205, the control circuit101 does not only stop the transmission of additional information butturns the transmission of the transmission signal from the transmissioncircuit 102 to the stopped state to alleviate battery consumption of thebattery 508 as much as possible when determining that the core body 506is in the protected state.

[Transfer of Signal between Electronic Pen 1C and Position DetectingDevice 200C]

As shown in FIG. 11, the position detecting device 200C that receives asignal from the electronic pen 1C in the third embodiment includes asensor 230 and a pen indication detecting circuit 240 connected to thesensor 230.

The sensor 230 of the position detecting device 200C of this example hasa configuration to receive a signal sent out from the transmission-typeelectronic pen 1C, detect the position indicated by the electronic pen1C, and receive additional information by using a sensor pattern formedby a group of first conductors and a group of second conductorsintersect.

For example, the group of first conductors is a group obtained bydisposing plural first conductors 231Y₁, 231Y₂, . . . , 231Y_(m) (m isan integer equal to or larger than 1) that extend along the horizontaldirection (X-axis direction) in the Y-axis direction in parallel, withthe plural first conductors 231Y₁, 231Y₂, . . . , 231Y_(m) separatedfrom each other by predetermined intervals.

Furthermore, the group of second conductors is a group obtained bydisposing plural second conductors 232X₁, 232X₂, . . . , 232X_(n) (n isan integer equal to or larger than 1) that extend along a directionintersecting the extension direction of the first conductors 231Y₁,231Y₂, . . . , 231Y_(m), specifically the vertical direction (Y-axisdirection) orthogonal to the extension direction in this example, in theX-axis direction in parallel, with the plural second conductors 232X₁,232X₂, . . . , 232X_(n) separated from each other by predeterminedintervals.

In the following description, regarding the first conductors 231Y₁,231Y₂, . . . , 231Y_(m), the conductors will be referred to as the firstconductor 231Y when there is no need to discriminate the respectiveconductors. Similarly, regarding the second conductors 232X₁, 232X₂, . .. , 232X_(n), the conductors will be referred to as the second conductor232X when there is no need to discriminate the respective conductors.

The pen indication detecting circuit 240 includes a selection circuit241 used as an input/output interface with the sensor 230, an amplifyingcircuit 242, a band-pass filter 243, a detection circuit 244, asample/hold circuit 245, an AD conversion circuit 246, and a controlcircuit 247.

The selection circuit 241 selects one conductor from each of the groupof first conductors and the group of second conductors based on acontrol signal from the control circuit 247. The conductors selected bythe selection circuit 241 are connected to the amplifying circuit 242,and a signal from the electronic pen 1C is detected by the selectedconductors and is amplified by the amplifying circuit 242. The output ofthe amplifying circuit 242 is supplied to the band-pass filter 243 andonly a component of the frequency of the signal transmitted from theelectronic pen 1C is extracted.

An output signal of the band-pass filter 243 is subjected to detectionby the detection circuit 244. An output signal of the detection circuit244 is supplied to the sample/hold circuit 245 and is sampled and heldat predetermined timing based on a sampling signal from the controlcircuit 247. Thereafter, the signal is converted to a digital value bythe AD conversion circuit 246. The digital data from the AD conversioncircuit 246 is read by the control circuit 247 and is processed.

The control circuit 247 operates to send out a control signal to each ofthe sample/hold circuit 245, the AD conversion circuit 246, and theselection circuit 241 based on a program stored in a read-only memory(ROM) inside the control circuit 247. Furthermore, the control circuit247 calculates position coordinates on the sensor 230 indicated by theelectronic pen 1C from the digital data from the AD conversion circuit246. Moreover, the control circuit 247 demodulates additionalinformation sent from the electronic pen 1C from the digital data fromthe AD conversion circuit 246.

FIG. 12 depicts a timing chart for explaining a signal of apredetermined pattern from the transmission-type electronic pen 1C ofthe present embodiment, received by the sensor 230 of the positiondetecting device 200C. In the electronic pen 1C of the presentembodiment, as shown in FIG. 10, the control circuit 101 determineswhether or not the core body 506 is in the state of being protected bythe cap 1Cb based on the sensor output of the magnetic sensor 519, andrepeatedly outputs the signal of the predetermined pattern composed of asignal for position detection and additional information from thetransmission circuit 102 when determining that the core body 506 is inthe unprotected state.

The additional information includes writing pressure data calculatedfrom the capacitance of the variable-capacitance capacitor 70C formed ofthe writing pressure detecting module 70, and the identificationinformation of the electronic pen 1C read out from the ID memory 104.

FIG. 12(A) shows an example of the control signal from the controlcircuit 101. As shown in FIG. 12(B), in a certain period during whichthe high level is kept, the transmission signal from the transmissioncircuit 102 is continuously transmitted as a burst signal (continuoustransmission period in FIG. 12(C).

The length of this continuous transmission period is set to time lengthin which an indicated position on the sensor 230 by the electronic pen1C can be detected in the pen indication detecting circuit 240 of theposition detecting device 200C. For example, the length is set to timelength in which all of the first conductors 231Y and the secondconductors 232X can be scanned one or more times, preferably pluraltimes.

In this continuous transmission period, the control circuit 101 detectsthe value of the writing pressure applied to the core body 506 as avalue according to the capacitance of the variable-capacitance capacitor70C formed of the writing pressure detecting module 70 by a methodsimilar to that described in the first embodiment, and obtains thewriting pressure value as a value of plural bits (e.g., 10 bits) (binarycode).

Then, as shown in FIG. 12(A), when the continuous transmission periodends, the control circuit 101 carries out ASK modulation of thetransmission signal from the transmission circuit 102 by controlling thecontrol signal to the high level or low level at a predetermined cycle(Td). At this time, the control circuit 101 invariably sets the controlsignal to the high level in the first round of the predetermined cycle(Td) and employs it as a start signal in FIG. 12(C). This start signalis a timing signal for allowing the subsequent data transmission timingto be accurately determined on the side of the position detecting device200C. It is also possible to utilize the burst signal of the continuoustransmission period as the timing signal instead of this start signal.

The control circuit 101 controls the transmission circuit 102 tosequentially transmit writing pressure data of plural bits subsequentlyto the start signal. In this case, as shown in FIG. 12(A), the controlcircuit 101 carries out control in such a manner that the control signalis set to the low level and the transmission signal is not sent out whenthe transmission data (binary code) is “0” and the control signal is setto the high level and the transmission signal is sent out when thetransmission data (binary code) is “1.”

Furthermore, the control circuit 101 controls the transmission circuit102 to send out the identification information of the electronic pen 1C,itself, read out from the ID memory 104 as an ASK signal or an OOKsignal similarly to the above description subsequent to the writingpressure data.

The control circuit 101 repeatedly transmits the signal of the patterncomposed of the continuous transmission period and the transmission dataperiod like the above-described periods at a cycle based on control fromthe control circuit 101.

In the pen indication detecting circuit 240 of the position detectingdevice 200C, first the control circuit 247 supplies a selection signalto sequentially select the second conductors 232X₁ to 232X_(n) to theselection circuit 241 for example. Furthermore, when each of the secondconductors 232X₁ to 232X_(n) is selected, the control circuit 247 readsdata output from the AD conversion circuit 246 as a signal level. Then,if the signal level of none of the second conductors 232X₁ to 232X_(n)reaches a predetermined value, the control circuit 247 determines thatthe electronic pen 1C does not exist on the sensor 230, and repeats thecontrol to sequentially select the second conductors 232X₁ to 232X_(n).

If a signal at a level equal to or higher than the predetermined valueis detected from any of the second conductors 232X₁ to 232X_(n), thecontrol circuit 247 stores the number of the second conductor 232X fromwhich the highest signal level is detected and the number of the pluralsecond conductors 232X around it. Then, the control circuit 247 controlsthe selection circuit 241 to sequentially select the first conductors231Y₁ to 231Y_(m), and reads the signal level from the AD conversioncircuit 246. At this time, the control circuit 247 stores the numbers ofthe first conductor 231Y from which the highest signal level is detectedand the numbers of the plural first conductors 231Y around it.

Then, the control circuit 247 detects a position on the sensor 230indicated by the electronic pen 1C from the number of the secondconductor 232X and the number of the first conductor 231Y from which thehighest signal level is detected and the plural second conductors 232Xand the plural first conductors 231Y around them, stored in theabove-described manner.

After selecting the last first conductor 231Y_(m) by the selectioncircuit 241 and ending the detection of the signal level, the controlcircuit 247 waits for the end of the period of continuous transmissionfrom the electronic pen 1C. When detecting a start signal after the endof the continuous transmission period, the control circuit 247 carriesout operation of reading writing pressure data and data onidentification information and sends out the writing pressure data andthe data on identification information that are read to a host computeror the like to which the position detecting device 200C is connected.Then, the control circuit 247 repeats the above operation.

As described above, according to the electronic pen 1C of the thirdembodiment, the problem of ensuring of security of the additionalinformation and the problem of protection of the core body can besimultaneously solved also in the transmission-type electronic pen ofthe capacitive system.

Modification Example of Electronic Pen of Third Embodiment

The detection of whether or not the tip of the core body is in theprotected state is not limited to the configuration using the magneticsensor 519. For example, instead of the magnetic sensor 519, an opticalsensor may be provided to be capable of receiving light from theexternal at a position on the case main body 502 hidden by the cap 1Cbwhen this cap 1Cb engages with the case main body 502. In addition,whether or not the core body 506 is protected may be determined throughmonitoring of light detection output of this optical sensor by thecontrol circuit 101.

Furthermore, a switch member that is turned on or off when the cap 1Cbengages with the case main body 502 may be provided in the case mainbody 502 instead of the magnetic sensor 519, and whether or not the corebody 506 is protected may be determined through monitoring of theon/off-state of the switch member by the control circuit 101.

Moreover, the switch member may be configured to be turned off when thecap 1Cb engages with the case main body 502 and be turned on when thecap 1Cb is removed from the case main body 502 and the core body 506 isset to the exposed state. In addition, this switch member may beprovided between the battery 508 and the power supply circuit 103 and beused as a power supply switch. In this case, only when the cap 1Cb isremoved and the core body 506 becomes the exposed state, the switchmember is turned on and the voltage of the battery 508 is supplied tothe power supply circuit 103 and the supply voltage is provided to thecontrol circuit 101 and the transmission circuit 102. Then, the controlcircuit 101 controls the transmission circuit 102 to start transmissionof a signal for position detection and additional information. That is,in this case, the control circuit 101 does not need to monitor theon/off-state of the switch member but determines the presence/absence ofsupply of power based on the on/off-state of the switch member as thedetection result of the protected state of the core body 506 by theprotection mechanism to carry out control of transmission of theadditional information based on it.

Furthermore, the pen tip does not need to be formed monolithically withthe core body 506 and may be deposited on or joined to the tip of thecore main body or may be formed by two-color molding. In this case, theelectrically-conductive pen tip is electrically connected to a signalgenerating circuit through the core main body for example.Alternatively, if the core main body is also composed of anelectrically-conductive material, it suffices that the core main body iselectrically connected to the signal generating circuit. Furthermore, ifthe core main body is composed of an insulator, such as a resin, the pentip and the signal generating circuit can be electrically connected bydepositing a conductor film on the resin surface or providing apenetrating electrical conductor that penetrates the inside of the resinand electrically connecting the electrically-conductive film orpenetrating electrical conductor to the signal generating circuit.

Fourth Embodiment

The fourth embodiment is a modification example of the electronic pen ofthe capacitive coupling system in the third embodiment. The electronicpen 1C of the above-described third embodiment includes a signalgenerating circuit (oscillation circuit) and has the configuration inwhich a signal is sent out from the core body 506. In contrast thereto,in an electronic pen 1D of the capacitive coupling system in the fourthembodiment, a signal from a sensor of a position detecting device isreceived and a signal obtained by signal enhancement of the receivedsignal, such as amplification, is returned to the sensor of the positiondetecting device. A technique relating to transfer of signals by theelectronic pen 1D with the sensor is disclosed, for example, in detailin Japanese Patent Laid-Open No. 2012-221304.

The electronic pen 1D of the fourth embodiment wirelessly communicatesadditional information, such as data of the writing pressure applied tothe core body and identification information of the electronic pen, to aposition detecting device by a different channel from a signal forposition detection through a wireless communication circuit. Thewireless communication circuit is configured by a wireless communicationcircuit of a short-distance wireless communication standard, such as theBluetooth (registered trademark) standard.

Furthermore, a configuration in which a cap is engaged with theelectronic pen main body is similar to that of the above-described thirdembodiment. Also in the present embodiment, detection of the state inwhich the core body is protected by the cap and the state in which thecap is removed and the core body is not protected is carried out by themagnetic sensor for detecting the attachment and detachment of the capsimilarly to the third embodiment.

FIG. 13A is a diagram for explaining the electronic circuitconfiguration on the side of the electronic pen main body engaged withthe cap in the fourth embodiment. FIG. 13B is a sectional view along A-Ain FIG. 13A and is a sectional view of a pen tip part of an electronicpen main body 1Da of the electronic pen 1D of the fourth embodiment.

In the electronic pen 1D of the fourth embodiment, anelectrically-conductive core body 531 is disposed in such a manner thatthe tip protrudes from an opening part of a case 501D. In addition, aperipheral electrode 532 that surrounds the core body 531 is disposed.The peripheral electrode 532 may be disposed on the outercircumferential side surface of the case 501D or may be disposed on theinner wall surface of the case 501D. However, a configuration in whichthe core body 531 and the peripheral electrode 532 are insulated fromeach other is made.

In the electronic pen 1D of the fourth embodiment, an AC signal sent outfrom a sensor 230D of a position detecting device is received by theperipheral electrode 532 by capacitive coupling and the received signalis supplied to a transmission signal generating circuit 601 and a powersupply circuit 602. The power supply circuit 602 uses the AC signalreceived from the sensor 230D as a start trigger and generates a supplyvoltage from a voltage from a battery 603.

Then, the power supply circuit 602 provides the generated supply voltageto the transmission signal generating circuit 601 and the controlcircuit 604 and moreover to a wireless communication circuit 605.

The transmission signal generating circuit 601 enhances the AC signalfrom the sensor 230D received by the peripheral electrode 532 throughamplification or the like and then returns the signal after theenhancement to the sensor 230D through the core body 531 by capacitivecoupling.

Furthermore, the control circuit 604 monitors sensor output of amagnetic sensor 607 that sends out the sensor output according toattachment or detachment of the cap to or from the electronic pen mainbody 1Da, and carries out control to stop transmission of additionalinformation from the wireless communication circuit 605 when it isdetermined that the core body 531 is in the state of being protected bythe cap.

Moreover, when it is determined that the core body 531 is in the stateof being not protected by the cap from the sensor output of the magneticsensor 607, the control circuit 604 reads out identification informationof the electronic pen 1D from an ID memory 606 and transmits theidentification information as the additional information to a positiondetecting device 200D through the wireless communication circuit 605.Furthermore, the control circuit 604 calculates data of the value of thewriting pressure applied to the core body 531 from the value of thecapacitance of a variable-capacitance capacitor 70C formed of a writingpressure detecting module 70 that detects the writing pressure appliedto the core body 531, and transmits the writing pressure data as theadditional information to the position detecting device 200D through thewireless communication circuit 605.

Also in the electronic pen 1D of the fourth embodiment, in the state inwhich the core body 531 is protected by the cap, the transmission of theadditional information by wireless communication is stopped and securityis ensured.

Fifth Embodiment

The electronic pens 1 and 1M of the above-described first embodiment andsecond embodiment are the system in which the tip of the core body unitof the electronic pen cartridge is protruded and retracted based on theknock system. However, a system in which the tip of the core body unitof the electronic pen cartridge is protruded and retracted based on arotation system may be employed.

FIGS. 14A and 14B are diagrams for explaining a configuration example ofan electronic pen 1S of a rotation system in a fifth embodiment. Theelectronic pen 1S of the present embodiment is composed of an electronicpen main body unit 2Sa and a cap unit 2Sb rotatably fitted to theelectronic pen main body unit 2Sa. The electronic pen main body unit 2Saforms a first member and the cap unit 2Sb forms a second member.

The electronic pen main body unit 2Sa includes a protruding-retractingmechanism 701 that protrudes and retracts a tip 3Sa of the pen tip of anelectronic pen cartridge 3S based on the rotation system. The electronicpen cartridge 3S is inserted in the protruding-retracting mechanism 701and is held to the protruding-retracting mechanism 701. The cap unit 2Sbhas a configuration with which the cap unit 2Sb can rotate relative tothe electronic pen main body unit 2Sa and is fitted to theprotruding-retracting mechanism 701 to add rotation to thisprotruding-retracting mechanism.

The electronic pen cartridge 3S of the electronic pen 1S of the fifthembodiment has a different form from the above-described electronic pencartridges 3, 3B, 3R, and 3E and has a fitting part that is inserted inthe protruding-retracting mechanism 701 and is fixed to thisprotruding-retracting mechanism.

Furthermore, in the electronic pen 1S of the fifth embodiment, as shownin FIGS. 14A and 14B, the electronic pen main body unit 2Sa and the capunit 2Sb are provided with a magnetic sensor 702 and a permanent magnet703, respectively, at positions that become the state of being close toeach other due to the rotation of the cap unit 2Sb. In addition, themagnetic sensor 702 is connected to a control circuit that is providedin an electronic circuit in the electronic pen main body unit 2Sa andcontrols transmission of additional information similarly to the thirdembodiment.

Moreover, in the electronic pen 1S of the fifth embodiment, as shown inFIG. 14A, in the state in which the whole of the electronic pencartridge 3S is housed in the electronic pen main body unit 2Sa and thetip 3Sa is protected, the permanent magnet 703 and the magnetic sensor702 become the state of being comparatively remote. Therefore, magneticflux from the permanent magnet 703 is not detected in the magneticsensor 702 and the sensor output thereof becomes a low level.

When the cap unit 2Sb is rotated from this state and the state in whichthe tip 3Sa of the electronic pen cartridge 3S protrudes from theelectronic pen main body unit 2Sa and is unprotected is obtained, thepermanent magnet 703 and the magnetic sensor 702 become the state ofbeing close to each other. Therefore, the magnetic flux from thepermanent magnet 703 is detected in the magnetic sensor 702 and thesensor output thereof becomes a high level.

The control circuit provided in the electronic circuit in the electronicpen main body unit 2Sa monitors the sensor output of the magnetic sensor702. When the sensor output is at the low level, the control circuitdetermines that the tip 3Sa of the electronic pen cartridge 3S is in theprotected state, and carries out control to stop the transmission of theadditional information. Furthermore, when the sensor output is at thehigh level, the control circuit determines that the tip 3Sa of theelectronic pen cartridge 3S is not protected, and carries out control tosend out the additional information.

It goes without saying that effects similar to those of theabove-described embodiments are achieved also in the fifth embodiment.

The detection of whether or not the tip of the electronic pen cartridgeis in the protected state is not limited to the configuration using themagnetic sensor 702. For example, instead of the magnetic sensor 702, aswitch member that is turned on or off when the cap unit 2Sb rotatesfrom the state of FIG. 14A to the state of FIG. 14B may be provided inthe electronic pen main body unit 2Sa. In addition, whether or not thetip of the electronic pen cartridge is protected may be determinedthrough monitoring of the on/off-state of the switch member by thecontrol circuit.

Other Modification Examples

In the first embodiment and the second embodiment, the additionalinformation is transmitted with the signal for position detection to thesensor of the position detecting device through the resonant circuitprovided near the core body. However, the additional information, in thefirst embodiment and the second embodiment, may be transmitted to theposition detecting device through a wireless communication circuitseparately from the signal for position detection similar to the fourthembodiment. Furthermore, also in the third embodiment, the signal forposition detection may be transmitted to the position detecting devicethrough the electrically-conductive core body and the additionalinformation may be transmitted to the position detecting device througha wireless communication circuit.

In addition, in the case of transmitting the additional information tothe position detecting device by using a wireless communication circuit,all kinds of additional information may be transmitted through thewireless communication circuit. Alternatively, for example,identification information of the electronic pen or the electronic pencartridge in the additional information may be transmitted through thewireless communication circuit, and writing pressure data may betransmitted with the signal for position detection to the positiondetecting device.

Moreover, in the above-described embodiments, the detection result ofthe detecting means that detects whether or not at least the tip of thecore body is in the state of being protected by the protection mechanismis supplied to the control circuit and the control circuit controlswhether or not to allow transmission of the additional information.However, it is also possible to control whether or not to allowtransmission of the additional information based on the detection resultof the detecting means without going through the control circuit. Forexample, in the case of transmitting the additional information througha wireless communication circuit, whether or not to allow thetransmission of the additional information can be controlled by makingthe configuration to control the operation and non-operation of thewireless communication circuit based on the detection output of thedetecting means.

Furthermore, in the above-described second embodiment to fifthembodiment, the determination of whether or not at least the tip of thecore body is protected may be based on the output of the writingpressure detecting means that detects the writing pressure applied tothe core body.

Moreover, the electronic pen of the present invention may have aconfiguration that does not include the control circuit, itself,controlling whether or not to allow transmission of the additionalinformation based on the detection result of the detecting meansdetecting whether or not at least the tip of the core body is in thestate of being protected by the protection mechanism. For example, aconfiguration may be employed in which the electronic pen cartridge thatforms the electronic pen main body unit includes a circuit in which avariable-capacitance capacitor formed as a writing pressure detectingmember is connected in parallel to the resonant circuit composed of acoil and a capacitor.

In this case, in a position detecting device, the writing pressure isdetected based on change in the frequency of a signal from theelectronic pen (phase change is also available). Therefore, when theelectronic pen is in the state in which the tip of the core body isprotected by the protection mechanism, the writing pressure applied tothe pen tip is not detected and information on the writing pressure, asan example of the additional information, is not transmitted to theposition detecting device. Then, when the electronic pen becomes thestate in which the tip of the core body is not protected by theprotection mechanism, the state in which a writing pressure can beapplied to the tip of the core body is obtained. When a writing pressureis actually applied, the frequency of the resonant circuit changesaccording to the writing pressure and, as the frequency resulting fromthe change, information on the writing pressure as the additionalinformation is transmitted to the position detecting device.

In the above-described embodiments, the writing pressure detecting meansuses the variable-capacitance capacitor that varies the capacitance by amechanical movable part according to the writing pressure. However,writing pressure detecting means in which the variable-capacitancecapacitor is formed as a micro electro mechanical system (MEMS) chipformed of a semiconductor device may be used. Furthermore, it goeswithout saying that the writing pressure detecting means may be writingpressure detecting means that does not detect change in the capacitancebut varies an inductance value or a resistance value.

The invention claimed is:
 1. An electronic pen configured to transmitsignals to a sensor of a position detecting device, the electronic pencomprising: a core body; a signal transmitter which, in operation,transmits a signal for position detection and a signal includinginformation about the electronic pen to the sensor of the positiondetecting device; and a protector which, in operation, sets at least atip of the core body between a protected state and an unprotected state,at least the tip of the core body being unexposed to an environmentexternal to the electronic pen in the protected state, at least the tipof the core body being exposed to the environment in the unprotectedstate, wherein in response to at least the tip of the core body being inthe unprotected state, the signal for position detection and the signalincluding the information are transmittable from the signal transmitterto the sensor of the position detecting device, and in response to atleast the tip of the core body being in the protected state, the signalfor position detection is transmittable from the signal transmitter andthe signal including the information is not transmitted from the signaltransmitter.
 2. The electronic pen according to claim 1, comprising: acontrol circuit which, in operation, controls transmission of the signalfor position detection and the signal including the information inresponse to at least the tip of the core body being in the unprotectedstate, and controls non-transmission of the signal including theinformation in response to at least the tip of the core body being inthe protected state.
 3. The electronic pen according to claim 1,comprising: a writing pressure detector, wherein at least the tip of thecore body is determined to be in the unprotected state in response tothe writing pressure detector detecting writing pressure applied to thecore body.
 4. The electronic pen according to claim 1, comprising: afirst chassis having a tubular shape in which an electronic pen mainbody is disposed, the electronic pen main body including the core bodyand the signal transmitter; and a second chassis having a tubular shapeand including a fitting part, the electronic pen main body being fittedto the fitting part.
 5. The electronic pen according to claim 4, whereinthe protector includes a knock mechanism that switches at least the tipof the core body between the protected state and the unprotected state,the entire core body is disposed in the second chassis in the protectedstate, and at least the tip of the core body protrudes from the secondchassis into the environment in the unprotected state.
 6. The electronicpen according to claim 5, comprising: a switch that is turned on and offin conjunction with operation of the knock mechanism.
 7. The electronicpen according to claim 1, comprising: a tubular chassis that holds thecore body in a state in which at least the tip of the core body isprotruded from one opening; and a cap that engages with the tubularchassis to cover the tubular chassis from a side on which the tip of thecore body is protruded.
 8. The electronic pen according to claim 7,wherein at least the tip of the core body is in the protected state whenthe cap is engaged with the tubular chassis.
 9. The electronic penaccording to claim 1, wherein the protector includes: a first memberthat has a tubular shape and includes a protruding-retracting mechanismthat protrudes and retracts the tip of the core body from one openingbased on a rotation mechanism; and a second member that is rotatable tocommunicate rotation to the protruding-retracting mechanism of the firstmember.
 10. The electronic pen according to claim 9, wherein at leastthe tip of the core body is determined to be in the unprotected state inresponse to detecting rotation of the second member relative to thefirst member.
 11. The electronic pen according to claim 1, wherein theinformation about the electronic pen includes identification informationof the electronic pen.
 12. The electronic pen according to claim 1,comprising: a coil wound around a magnetic core positioned adjacent tothe core body; and a resonant circuit including a capacitor connected inparallel to the coil, wherein transmission and reception of signals arecarried out in the resonant circuit by electromagnetic inductioncoupling between the resonant circuit and the sensor of the positiondetecting device.
 13. The electronic pen according to claim 1,comprising: a signal generating circuit which, in operation, generatesthe signal for position detection and the signal including theinformation, wherein the core body has electrical conductivity, and thesignal transmitter transmits the signals from the signal generatingcircuit via the core body to the sensor of the position detecting deviceby capacitive coupling.
 14. The electronic pen according to claim 1,wherein the core body has electrical conductivity and a peripheralelectrode is provided around the core body, a signal from the sensor ofthe position detecting device is received through one of the core bodyand the peripheral electrode by capacitive coupling, and a signalgenerated based on the signal from the sensor is transmitted from theother of the core body and the peripheral electrode to the sensor of theposition detecting device by capacitive coupling.
 15. The electronic penaccording to claim 1, wherein the signal transmitter includes a wirelesscommunication circuit that transmits part or all of the information tothe position detecting device through a wireless communication path. 16.A method, comprising: providing an electronic pen including a core body,wherein at least a tip of the core body is settable between a protectedstate and an unprotected state, at least the tip of the core body beingunexposed to an environment external to the electronic pen in theprotected state, at least the tip of the core body being exposed to theenvironment in the unprotected state; in response to at least the tip ofthe core body being in the unprotected state, entering a first state inwhich a signal for position detection and a signal including informationabout the electronic pen are transmittable from the electronic pen; andin response to at least the tip of the core body being in the protectedstate, entering a second state in which the signal for positiondetection is transmittable from the electronic pen and the signalincluding the information is not transmitted from the electronic pen.17. The method of claim 16, comprising; determining whether pressure isapplied to the tip of the core body; determining that at least the tipof the core body is in the protected state in response to determiningthat pressure is applied to the tip of the core body; and determiningthat at least the tip of the core body is in the unprotected state inresponse to determining that no pressure is applied to the tip of thecore body.
 18. The method of claim 16, comprising: determining whether aswitch is in an on state or an off state; determining that at least thetip of the core body is in the protected state in response todetermining that the switch is in the off state; and determining that atleast the tip of the core body is in the unprotected state in responseto determining that the switch is in the on state.
 19. The method ofclaim 16, comprising: determining whether a cap is engaged with a mainbody of the electronic pen; determining that at least the tip of thecore body is in the protected state in response to determining that thecap is engaged with the main body of the electronic pen; and determiningthat at least the tip of the core body is in the unprotected state inresponse to determining that the cap is not engaged with the main bodyof the electronic pen.
 20. An electronic pen configured to transmitsignals to a sensor of a position detecting device, the electronic pencomprising: a core body having electrical conductivity; a peripheralelectrode provided around the core body; a signal transmitter which, inoperation, transmits a signal for position detection and a signalincluding information about the electronic pen to the sensor of theposition detecting device; and a protector which, in operation, sets atleast a tip of the core body between a protected state and anunprotected state, at least the tip of the core body being unexposed toan environment external to the electronic pen in the protected state, atleast the tip of the core body being exposed to the environment in theunprotected state, wherein in response to at least the tip of the corebody being in the unprotected state, the signal for position detectionand the signal including the information are transmittable from thesignal transmitter to the sensor of the position detecting device, inresponse to at least the tip of the core body being in the protectedstate, the signal including the information is not transmitted from thesignal transmitter, a signal from the sensor of the position detectingdevice is received through one of the core body and the peripheralelectrode by capacitive coupling, and a signal generated based on thesignal from the sensor of the position detecting device is transmittedfrom the other of the core body and the peripheral electrode to thesensor of the position detecting device by capacitive coupling.